feat(stock): batch movement ledger, production batches and shop write-back API

One remaining quantity per batch, kept in ApiCore and always derived:
initial quantity (jarCount / produced quantity) plus the signed movements
in the new BatchMovement ledger, which is never deleted.

- Production batches for MANUFACTURED articles (candles, propolis
  products, ...); articles get a kind and a shop category.
- Withdrawals (farm shop, own use, breakage, sample) and inventory
  corrections on bottlings and production batches, never more than the
  remaining stock; every write locks the bottling or the article row.
- Shop bookings via POST /shop-sync/movements (new scope
  shop-sync:write): idempotent per externalId, articles allocated oldest
  best-before first, returns mirrored onto the batches of the sale,
  invalid entries rejected one by one.
- GET /shop-sync/stock and remainingCount in the shop feed; webhook
  stock.changed after every change (ids only, receivers fetch numbers).
- Bottlings and production batches with movements cannot be deleted.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Backend/prisma/schema.prisma

@@ -120,6 +120,8 @@ model User {
   colonyMoves           ColonyApiaryHistory[]
   auditLogs             AuditLog[]
   bottlingBatches       BottlingBatch[]
+  productionBatches     ProductionBatch[]
+  batchMovements        BatchMovement[]
   notifications         Notification[]
   queenEvaluations      QueenEvaluation[]
   webhookSubscriptions  WebhookSubscription[]
@@ -979,6 +981,22 @@ enum ProductStatus {
   DISCONTINUED
 }
 
+// Wo der Bestand eines Artikels liegt: Honig je Abfuellung (BottlingBatch),
+// alles andere (Kerzen, Propolis-Produkte, ...) je Herstellungscharge
+// (ProductionBatch). Nicht umstellbar, sobald Chargen existieren.
+enum ProductKind {
+  BOTTLED_HONEY
+  MANUFACTURED
+}
+
+// Vorgabe fuer die Kategorie des Produkts im Webshop (Wabenhain).
+enum ShopCategory {
+  HONIG
+  KERZEN
+  PROPOLIS
+  SONSTIGES
+}
+
 model Product {
   id            String        @id @default(cuid())
   name          String
@@ -988,10 +1006,13 @@ model Product {
   weight        Float?
   salesUnit     String?
   status        ProductStatus @default(ACTIVE)
+  kind          ProductKind   @default(BOTTLED_HONEY)
+  shopCategory  ShopCategory  @default(HONIG)
   createdAt     DateTime      @default(now())
   updatedAt     DateTime      @updatedAt
 
-  bottlingBatches BottlingBatch[]
+  bottlingBatches   BottlingBatch[]
+  productionBatches ProductionBatch[]
 
   @@index([status])
 }
@@ -1046,10 +1067,106 @@ model BottlingBatch {
   user           User?      @relation(fields: [userId], references: [id])
   createdAt      DateTime   @default(now())
 
+  movements BatchMovement[]
+
   @@index([honeyBatchId])
   @@index([productId])
 }
 
+// ---------------------------------------------------------------------------
+// Herstellungschargen und Bestandsbewegungen (Bestandsabgleich mit dem Shop,
+// docs/superpowers/specs/2026-10-02-bestandsabgleich-design.md)
+// ---------------------------------------------------------------------------
+
+// Gegenstueck zur Abfuellung fuer Artikel der Art MANUFACTURED (Kerzen,
+// Propolis-Tinkturen, Salben, ...). Spaeter Ziel eines Herstellungslaufs, der
+// Rohstoff-Chargen verbraucht.
+model ProductionBatch {
+  id             String    @id @default(cuid())
+  productId      String
+  product        Product   @relation(fields: [productId], references: [id])
+  lotNumber      String    @unique
+  date           DateTime
+  // Hergestellte Stueckzahl - Ausgangsmenge fuer den Rest.
+  quantity       Int
+  bestBeforeDate DateTime?
+  notes          String?
+  userId         String?
+  user           User?     @relation(fields: [userId], references: [id])
+  createdAt      DateTime  @default(now())
+  updatedAt      DateTime  @updatedAt
+
+  movements BatchMovement[]
+
+  @@index([productId])
+}
+
+enum BatchMovementType {
+  SHOP_SALE
+  SHOP_RETURN
+  WITHDRAWAL
+  CORRECTION
+}
+
+enum WithdrawalReason {
+  HOFLADEN
+  EIGENBEDARF
+  BRUCH
+  PROBE
+  SONSTIGES
+}
+
+// Bewegungsbuch: jede Bestandsaenderung einer Charge, nie geloescht (Fehler
+// werden gegengebucht). Rest = Ausgangsmenge + Summe aller quantity.
+// Genau eine der beiden Chargen-Spalten ist gesetzt (CHECK-Constraint in der
+// Migration).
+model BatchMovement {
+  id                String            @id @default(cuid())
+  bottlingBatchId   String?
+  bottlingBatch     BottlingBatch?    @relation(fields: [bottlingBatchId], references: [id], onDelete: Restrict)
+  productionBatchId String?
+  productionBatch   ProductionBatch?  @relation(fields: [productionBatchId], references: [id], onDelete: Restrict)
+  type              BatchMovementType
+  // Mit Vorzeichen: minus = raus, plus = rein.
+  quantity          Int
+  reason            WithdrawalReason?
+  notes             String?
+  shopRequestId     String?
+  shopRequest       ShopStockRequest? @relation(fields: [shopRequestId], references: [id], onDelete: Restrict)
+  userId            String?
+  user              User?             @relation(fields: [userId], references: [id])
+  apiKeyId          String?
+  createdAt         DateTime          @default(now())
+
+  @@index([bottlingBatchId])
+  @@index([productionBatchId])
+  @@index([shopRequestId])
+}
+
+enum ShopStockRequestKind {
+  SALE
+  RETURN
+}
+
+// Eine Buchungsanfrage des Shops. externalId (vom Shop vergeben) macht jede
+// Anfrage idempotent: dieselbe Anfrage zweimal bucht nur einmal.
+model ShopStockRequest {
+  id                 String               @id @default(cuid())
+  externalId         String               @unique
+  kind               ShopStockRequestKind
+  // Ziel: eine Abfuellung (Honig) ODER ein Artikel (MANUFACTURED, FIFO).
+  bottlingBatchId    String?
+  productId          String?
+  quantity           Int
+  reversesExternalId String?
+  apiKeyId           String?
+  createdAt          DateTime             @default(now())
+
+  movements BatchMovement[]
+
+  @@index([reversesExternalId])
+}
+
 // ---------------------------------------------------------------------------
 // Inventar (Abschnitt 4.22) – v1.x Modul 24
 // ---------------------------------------------------------------------------